Stabilizing arctic ground cover

ABSTRACT

Described are techniques for stabilizing, restoring the groundcover in Arctic (or like, frozen) environments including, in specific embodiments, techniques for: restoring and revegetating a spoil pond for spent drilling mud; refreezing and insulating of &#39;&#39;&#39;&#39;pond crossings&#39;&#39;&#39;&#39;; restoring &#39;&#39;&#39;&#39;winter roads&#39;&#39;&#39;&#39; and like tundra scars; leveling &#39;&#39;&#39;&#39;arctic roads&#39;&#39;&#39;&#39; and constructing ice foundations for arctic pads.

United States Patent 1191 Condo et al. 45 J 25, 1074 [54] STABILIZING ARCTIC GROUND COVER FOREIGN PATENTS OR APPLICATIONS [75] Inventors: Newtown Square 262,800 4/1964 Australia 61/36 A W Neubauer, 5,808 7/1903 Denmark ..l66/DIG 1 Burlmgton, Iowa 2 6 l 5 10/1353 Finland;.. ....6l/43 [73] Assi nee: Atlantic Richfield C N g York, ew OTHER PUBLICATIONS i I The Oil and Gas Journal Nov. 16, 1970, p. I70. [22] Wed 1972 Permafrost Or Permanently Frozen Ground and l PP 227,664 Related Engineering Problems, by Simon William Muller, J. W. Edwards Inc. (Publisher), Ann Arbor, 52 us. Cl 61/50, 61/36 A, 62/259, M 1947 ava'lab'e 404/72, 111/1 Hfi; Lr taryt I [51] Int. Cl..... E02d 17/18, E02d 3/10, E02d 27/32 I [58] Field of Search 94/22, 7; l66/DlG. 1; Primary Examiner-Mervin Stein 1/36 A, 50; 5 Assistant Examiner-Alex 61052 [56] Attorney, Agent, or Firm-Coleman R. Reap References Cited UNITED STATES PATENTS [57] ABSTRACT 3,l35,097 6/1964 sql'lunberg 6l/36 A De cribed are techniques f r tabilizing, restoring the ,7 4,91 7 "/1967 v'gnov'ch 61/36 W- ground-cover in Arctic (or like, frozen) environments 3,267,237 lpDougan ..61/36A including in specific embodiments techniques f 2 78 23 1 10/1966 storing and revegetating a spoil pond for spent drilling 3250188 371g rg fi 94/7 mud; refreezing and insulating of pond crossings; 3223005 12/1965 Carlson 54/22 restoring winter roads" and like tundra scars; level- 3 153 912 1071964- Rm....11111111111111:111111116150 ing arctic roads and Constructing ice mundations 829,247 g/ 1 296 Badger ..94/22 forarctlc Pads- 4 C a m li f rsw s BACKGROUND OF THE INVENTION Some arctic roads comprise simply a layer or gravel spread upon the Arctic plain, over the tundra and underlying permafrost, with the result, that, over a period of time, the roadsides, and any ditches that may have developed there, fill with water presenting an obvious hazard, both to the integrity of the road and to the stability of the adjacent Arctic groundcover.

A related problem exists where winter roads are constructed; these comprising simply a piling-up of frozen ground cover during, winter (e.g., by bulldozers simply blading-up tundra on one or both sides of the right of way) to present a raised earthenl-tundra berm above the surrounding ice and snow, typically a few feet high and a few feet wide. Such winter roads" are being discouraged at present, with the existing berms being destined for leveling and later restorationof the native vegetation, etc. However, when the tundra back-fill is distributed back over the marginal ditches (now typically eroded or subsided), a gulley often remains .which, if not treated, will leave a gash externally scarring the natural topography of the arctic plain. It is well-known that such scars are often selfperpetuating and self-eroding in time and, thus, must be prevented or corrected wherever possible. Contemporary restoration methods involve filling the marginal ditches with grave] or arctic dune sand to bring the eroded section up to tundra grade, thereafter distributing the tundra material on this and reseeding. Unfortunately, this technique isjnot only expensive but, due to the poor insulation such materials provide typically fails to prevent melting of the subjacent permafrost and eventual erosion or subsidanc'e. Similar problems result from vehicular tracks left in the soft summer tundra and from thin-layer gravel roads.

A related problem exists with mud sumps or other spoil ponds, such as are found adjacent to oil field drilling pads on the Alaskan North Slope. Mud Sumps or many types may be found in the Alaskan and Canadian Arctic as a result of past drilling operations, many being abandoned in various stages of disrepair. These sumps are typically built simply by the excavation of a cavity in the tundra and the piling up of excavated soil and vegetation to form a berm perimeter around the cavity, thereby defining a sump pond in which drilling mudis to be kept. Spent drilling mud is at times left in such a pond without any further disposal efforts.

However, it is presently advisable to remove the mud and dispose of it in a less offensive manner and fill the cavity with earth material. Typically, a sump base-level is close to tundra grade with its perimeter berm about feet above grade. It is obviously important to restore this berm material back over the tundra surface (e.g., to cover the sump pit) as well as to remove the excess spent mud and dispose of it in a practical, economical and ecological]y-satisfactory fashion. The temptation is to scatter the mud about, e.g., over the adjacent tundra or along nearby gravel roads to the involved drilling site. However, certain muds (in excess) may have a toxic effect on tundra vegetation and/or present a dust problem since it comprises a fine aqueous suspension readily drying to a light, fine dust. Similarly, it is very unsatisfactory, if not hazardous, as a roadway coating. Also, it is rather expensive to dispose of mud in such a manner. Moreover, the presence of such spoil ponds atop a permafrost formation, increasing its susceptibility to melting, obviously presents the hazard of melt-subsidance and serious erosion.

As an answer to the foregoing and related problems, we have developed techniques according to various features of the present invention that involve such expedients as freezing the liquid formation (in such a rain-ditch or spoil-pond area); and then restoring these areas to become an integral part of the subjacent permafrost by covering them with sufficient insulation to keep them frozen, laying on earth-fill over the insulation (e.g., with berm material) to restore the area to tundra grade, and then a special reseeding treatment a for restoration of tundra vegetation. According to some more particular features, a very simple, inexpensive foam insulation may be used, together with certain optimal techniques of seed selection, fertilization and application.

ARCTIC GROUND COVER Land masses above the Arctic Circle typically exhibit a tundra ground cover made up of a biological insulating mat, 2 to four inches thick and comprises of various sedges, grasses, miniature shrubs, etc. Beneath this mat is an active layer of top-soil 6 to 18 inches thick, ordinarily made up of slit, sand and organic matter (this supporting the tundra vegetation). Below the active layer one typically finds a permafront stratum; i.e., an aqueous mixture of earth (rock, soil) material in various proportions (and sometimes comprising pure ice) and extending as far down as 1,000 feet or more. The active. layer of the tundra will thaw each summer, with the insulative properties of the tundra and the degree days of summer thaw controlling the depth of thaw in the active layer. In the winter, air temperatures can dip below 60F., with wind velocities up to and even exceeding 50 mph. Because this climate is so frigid and the arctic summer so brief (typically a few weeks) i and because the average temperature of the groundsurface is so low, the vegetative growth each year is typically miniscule. Moreover, many tundra soils are nearly sterile with extreme deficiencies in more than one of the primary nutrients (nitrogen, phosphate and potash). The typical grass and brush vegetation is thus quite sparse, dwarfed and starved; moreover, organic decay and bacterial action are extremely slow and seed yields are often low. Thus, understandably, natural revegetation of tundra is a very slow, tedious affair, and

all too unpredictable.

After some study and evaluation of typical tundra vegetation systems, a reseeding program was proposed with the following objectives:

TABLE I RESEEDING OBJECTIVES 1. Establishment of grasses in damaged areas by introduction of specially-selected, seeds which germinate rapidly and grow vigorously in the limited Arctic growing season;

2. Propagation and proliferation of native grasses in restored areas by stimulation, peripheral vegetation to enhance reinvasion and restore natural vegetative insulation over permafrost formations; and

3. Stimulation of native seed production on peripheral undisturbed areas by use of selected, specially formulated fertilizers and supplements to promote this 'reinvasion of prior restored areas and gradual return to the natural state.

In support of this program, an investigation was undertaken of typical soil nutrients with a view towards formulating adequate fertilizers for the foregoing objectives. Soil samples were taken from the plantsupporting active soil layer in the Prudhoe Bay and Sagwon areas of the Alaskan North Slope. The results are shown in Table 11 below.

(:1) Amounts based on agricultural crop production in Ihl. Continental 11.8.

Both samples evidence an excess of calcium and sodium. Boron, sulfur and manganese appear sufficient to support plant growth; however, deficiencies were found in available phosphorus, potassium, nitrogen, zinc and copper and iron; while pH was somewhat too alkaline. A similar soil sample taken at the Prudhoe Bay location, adding subsurface samples and giving the results indicated in Table III below.

TABLE III TUNDRA SOIL SURFACE AND PERMAFROST ANALYSIS (PRUDHOE BAY) DEPTH l2 l3 17 18 (11.)

Water (Wt. 23.8 62.4 80.4 34.5 17.5 13.7 8.0

pH 7.8 7.4 7.3 7.9 8.3 8.4 8.5 p (lb./acre) l3 9 5 8 l0 9 p (lb /Rcre) 20 23 43 72 88 69 K 0 70 20 1 15 125 250 290 105 (lb/acre) Ca 9800 18,000 14,000 7800 8200 8000 3400 (lb/acre) Mg 400 400 760 200 280 280 280 (lb/acre) Mn 46 28 29 47 43 40 57 (lb/acre) Zn 1 2 6 l l 3 2 (lb/acre) Fe 104 256 262 61 104 122 122 (lb/acre) Cu 5 7 6 v 5 4 7 s (lb/acre) B (lb/acre) 1.3 1.1 2.2 4.8 1.2 0.6 2.0

In accordance with a feature of the instant novel tundra restoration system, a special tundra fertilizer, Tundra Special-70", was developed to increase soil fertility, being formulated especially for a Prudhoe Bay locale. This was to be applied at approximately 600 pounds/acre concentration, being formulated to add P 0 K 0 and N plus trace minerals as indicated in Table IV below.

TABLE IV TUNDRA SPECIAL- FERTILIZER Component Percent by Weight N (Nitrogen) 11,52 P 0 (Phosphate) 34.56 K 0 (Potash) 8.64 Ca (Calcium) .03 Mg (Magnesium) .21 SO, (Sulfate Sulfur) 4.57 Al (Aluminum) B (Boron) 0.0392 Cu (Copper) 0.1344 Fe (Iron) 0.676 Mn (Manganese) 1.0768 Zn (Zinc) 1.01 Mo (Molybdenum) 0.00098 Inert Filler Balance Very little nitrogen release from the existing organic matter may be expected in such locales and is believed to be a temperature-dependent, bacteriological function. It is known that the nitrogen-converting bacteria (nitrosomonas and nitrosococci) are less active at 50 F., and become virtually ineffective at lower soil temperatures. At Prudhoe Bay the mean annual soil surface temperature is typically about 12 F.; whereas a typical value for mean soil surface temperature in an 800 degree day summer will be 40 F.

It is estimated that the top 2 inches of soil in each acre of this locale comprises approximately 666,000 lbs. of soil containing approximately 40,000 lbs. of nitrogen. It is estimated that the nitrogen release is not more than about .025 to 1.0 percent annually, or not more than 10 to 40 pounds of nitrogen released per acre per year. By comparison, the nitrogen release in typical organic soils in the lower 48 ranges from 1 to 5 percent annually, or 20 to pounds per acre per year. Accordingly, this special fertilizer was especially fortified with nitrogen. In certain other locales, ammonium nitrate is added as a supplemental nitrogen source.

SEED SELECTION The preferred approach for revegetating disturbed tundra areas is to reintroduce native biological species. As a matter of convenience, arctic grasses are preferred over other Arctic flora. Table V summarizes a survey of plant forms around the Naval Arctic Research Laboratory at Point Barrow, Alaska. It is representative of the Arctic flora (particularly grass species) found in much of the North Slope.

TABLE v ARCTIC FLORA BARROW, ALASKA (BASED ON TAXONOMICAL STUDY BY HULTEN) Family Generic Class Variety Common Name lzquisitaceae Horsetail GraminL-ac Hierochlrie alpina Holy grass (rocks and acid soils) Hierochloe pauciflora Holy grass Alopecurus alpinus Foxtail grass Phippsia algida Arctagrostis latifolia C alamagrostis neglecta borealis Deschampsia caespitosa Hair grass orientalis Trisetum spicatum Poa alpigena Blue grass (alpine) Poa arctic-a Blue grass (arctic) Poa glauca Arctophila fulva Dupontia Fisheri Marsh grass Puccinellia phryganodcs Goose grass Puccinellia Langeana (loose grass Festuca brachyphylla Fcscue grass Elymus arenarius mollis Lyme grass Cyperaceae Sctlgc family Juncaccac Rush family Salicaceac ,Willow family Polygnnaceae Buckwheat family Caryophyllaceae Pink family Ranunculaceae Crowfoot family Papaveraccae Poppy family Cruciferae Mustard family Saxifragaceae Saxifrage family Rosaceae Rose family Leguminosae Legume family Ericaceae Heath family Primulaceae Primrose Family Haloragaceae Water nilfoil family Polemoniaceae Poloneum family Boraginaceae Borage family Scrophulariaceae Figwort family Compositae Sunflower family Native seeds for revegetation were considered; however, seed production of Arctic tundra biospecies is not very predictable since their seed set appears significant only in those years having over about 800 degree days of thaw. Below this thaw index, native seed production will be low; above it, a fair to good seed yield can be realized. Also, harvesting seeds from actual tundra flora would require running the associated equipment over the soft delicate tundra surface during summer the time of maximum seed-set and of maximum thaw penetration. Such a harvest operation would, in itself, likely cause damage. On the other hand, cultivated production of such seeds at the commercial level will require years of development. Thus, for instant introduction of revegetation in disturbed tundra areas, using native seeds does not appear feasible at present.

Accordingly, commercially-available seeds whose generic characteristics bear a relationship to those of native species were screened. Well over a hundred grass types were considered before 13 winter-hardy" strains (from northern climates) were selected, these being listed in Table VI below.

TABLE VI GENERIC RELATION OF INTRODUCED VS NATIVE TUNDRA-TYPE Wild Oatsv Avena fatua L. sativa 65 hiemalis Tickle Agrostis Agrostis horealis 65 Grass (Walt) B.s.P.

Creeping Festuca rubra L. Festuca brachyphylla 83 Red Festuca haffinensis 83 Feseue l cstuca ruhra 75 Brome Brnmus inermis Bromus pumpellianus (i5"-72 Grass (leyss) Bromus arcticus 72 Perennial Lolium perenne Lolium multiflorum (mm-65 Rye Canada Poa Compressa alpegina 7245? Poa Blue L. Poa arctica 72-79 Poa glauca 72-82 Poa abbreviata 82 Poa flexuosa 7282 Poa hartzii 7282 Poa laxa 7282 Poa nascopieana 72-82 Poa pratensis 72-82 Reed Phalaris arun- Phalaris arundinacea 60-65 Canary dinacea Grass Slender Agropyron 82 Wheat pauci- Grass florum (Schwein) Agropyron Iatiglume Stream Agropyron Bank riparium Wheat (Scribn.

and Smith) Elbin Rye Secale cereale described,

Investigations with various seeds and appropriate fertilization indicated that red top, creeping red f'escue and brome did well when properly fertilized. Also, a cover crop of oats or barley appear to be quite beneficial for good seedling development. Moreover, fertilization tends to increase percent germination and promote good seedling development.

Seeds were also treated with gibberellic acid (GA), as a growth hormone. Most seeds treated with GA. and Water will exhibit better overall germination, the concentration varying however; with seedling development being usually observed on the order of l to 2 weeks ahead of that in untreated and fertilized plots (see Table vn TABLE VII SAMPLING A: PHENOTYPE RATINGS OF GRASS TYPES IN GROWTH HORMONE TEST GA. CONCENTRATION SOURCE 25 ppm 50 ppm 100 ppm Water only Red Top Russian Wild Rye Couch Grass Wild Oats Tickle Grass Ereeping Red Fescue Brome Grass Seedling dcvelopmcnt'ralings: Very Good: V.G.; Good: (1.; Fair: F.; Poor: P,; Very Poor: VP

Several grasses did not respond to differential growth hormone treatment. These are Brome, Olds Red Fescue, Meadow Foxtail, Boreal Red Fescue, Timothy, Elbin Rye, Israel Sweet Clover and Meadow Fescue. Conversely, some responded to high concentrations of GA (100 ppm), namely: Perennial Rye, Canada Blue, Stream Bank Wheat, Nugget Blue, Slender Wheat and Creeping Red Fescue.

Surprisingly, some species performed best with incipient water treatment alone, indicating that a 25 to 100 ppm concentration produced an inhibiting effect upon germination. These were: Arcta Red Fescue. Other grass species showed better response with 50 and I ppm; namely: Perennial Rye and Tickle Grass.

In summary, Red Top, Creeping Red Fescue, Brome and Canada Blue Grasses planted in the Prudhoe Bay area on disturbed tundra and gravel areas exhibited good winter survival and growth continuation surprisingly so in view of past knowledge and experience! Also noteworthy were the advantages derived from growth hormone treatments; namely, enhancing initial germination and growth, as well as reducing residual seed germination (seed that did not germinate the 1st year) and winter kill. Hormone treatment however is a very selective thing, since some of the specimen grasses did as well with a simple water pre-soak as with a 25 ppm GA treatment (1 years growth as the standard).

POND STABILIZATION EXAMPLE GENERAL Now, a specific example of using the tundra icing/restoration techniques according to the invention will be described in connection with rehabilitating a spoil pond (or sump) for drilling mud which was built on the tundra in the Alaskan Prudhoe Bay area. Such a sump is typically constructed by excavating a cavity of suitable size (here: I00 l50 feet; 6 feet below tundra grade) 8 into the arctic plain, piling up active layer and tundra material to form a suitable perimeter barrier (or berm) above grade (here, about 4 feet above grade; and about 10 feet wide). An underlying permafrost stratum will, as expected, be understood (here, beginning about 5 feet below grade, the excavation, thus cutting into the top foot of permafrost here). This sump, as is typical, will be understood as located adjacent a drilling pad and substantially filled with spent drilling mud. It is further understood that the warm mud and ambient heat will have caused a degree of meltsubsidance in the underlying permafrost, thus creating a waste liquid pool considerably deeper than originally constructed (note: this sump has lain abandoned for about a year with its liquid level equilibrating at about 6 feet below grade). During the early spring," preferably at the beginning of April, this spoil pond is to be iced-in and insulated, and restored according to the invention. (Ice formations are at their coldest and at their greatest depth at this time of year in this locale).

The general approach will be to apply a thin protective pre-coat (preferably using a crude-oil base) to the surface of the frozen mud. However, it is also preferred to first cut away the inner shoulder of the berm to form an inclined inner shelf" about 1 to 2 feet wide (around the inside of the berm and extending outward from the edge of the frozen mud and downward at about 45 therebeyond). When insulation-coated, this inner shelf accommodates a downwardtilting brim extension of the liquid (insulation) cap, about 1 foot wide. A urethane foam insulation coating is then applied to a thickness of 1 to 2 inches. Thisis followed by a barrier coating (preferably, but not limited to, a mixture of polymers in a petroleum base) for a weather seal. Thereafter, the berm is pushed in over the coated insulation cap as reseedable fill, sufficient to restore the grade level. The top surface of this fill is then fertilized and planted in a prescribed specified manner (tailored to the vegetative needs of the subject locale).

The leveling fill, once covered with revegetation, will function, as thermal insulation over the underneath permafrost, as will the insulated pond-ice, acting to stabilize the site, restoring it to ecologically-compatible integrity with the native ground cover, with the permanently-frozen mud-ice being kept frozen to be integrated with the underlying permafrost (forming a quasi-permafrost) and so providing a solid, stable footing for revegetation and for restoration and total integrationwith the surrounding native site.

POND-STABILIZATION: DETAILS The foregoing restoration steps will now be described in more detail.

PHASE 1 PRECOAT:

The X feet) frozen surface of the pond, together with the peripheral shoulder, are coated with a warm layer of ARCOTE or other suitable precoat to a depth of about 15 mils., this being applied generally as known in the art, using conventional manual hotspray equipment, heated to about 75F. (for typical April conditions in this locale) so as to help fiow the precoat onto the substrate and get fast set up. Although other equivalent materials will come to mind, this ARCOTE is the preferred polymer-extended crude-cut, comprising an homogeneous mixture of Prudhoe Bay residual crude" (from a diesel top with polybutadiene as a polymeric extender, or with a like extender (e.g., polyethylene or polystyrene). Of course, any application method, temperature, etc. will serve that applies the material in a quick, even coating as understood by those skilled in the art. Other petroleum base pre-coat materials may be used such as residual fuels, or even certain resins; however, it will be appreciated that for the subject locale, the aforementioned Prudhoe residual cut is especially convenient, inexpensive and practical. The extender materials may comprise any compatible polymeric checking agents which act to promote formation of a skin" upon coolg-. PHASE 2 FOAM INSULATION Once the pre-coat has sufficiently fset-up so as it be relatively firm (skin formed), a layer of polyurethane foam about 1.3 to 1.5 inches thick is applied thereover and allowed to cure, at least until it is set up. A different pre-coat may be called for with various differing ambient (thermal, soil, moisture, etc.) factors and/or different purposes (see' also copending, commonlyassigned U.S. Application Ser. No. 205,381 entitled Structure for Protecting and Insulating Frozen Substrates and Method for Producing Such Structures by A. C. Condo, G. R. Knight, G. R. Burt, and A. E. Borche r t,.filed Dec. 6, 1971. Although equivalent foam systems may be used (e.g. other urethane foams), it is preferred to use ARCOFOAM-1 system having the characteristics indicated in Table VIII below:

TABLE VIII: ARCOFOAM-l Compression strength (psi) at yield 43-50 Compression at yield 3.5-5.0

Density (pcf) 2.7-2.8 k-Factor, aged (new 0.] l0.l3) 0.15 BTU/M/sf/F/in Closed cells /c) v 89.5

Open cells ("lc) 6.8

Cell Walls (/c) 3.7

Curing Time at least -15 min. (here) Water Vapor Transmission (perms) 3.5

Although other conventional foam spray equipment may beused, a Gusmer pneumaticmix spray apparatus is preferred here (Gusmer Coating Co., Inc. Woodbridg e, N .J having a heater that provides a block temperature of about 140F. and hose temperature of about ll2l 18F. This ARCOFOAM 1 system is (as is conventional) developed by mixing and spraying a combination of polymeric isocyanate, (here ARCOFOAM-ISO-l is preferred) plus a polyol mixture, (here ARCOFOAM- OL- l being preferred) to finally cure on the substrate. ARCOFOAM-OL-l comprises a mixture of polymeric, polyether polyols containing trichlorofluoromethane catalyst and other additives plus some free isocyanate. ARCOFOAM-ISO- 1v -is a polymeric isocyanate of heavy viscosity (about 250 centipoise at 65F). The properties of the resultant rigidfoam as applied and polymerized in situ (summarized in Table Vlll) may, of course, be substantially met with any other like system.

Where the urethane foam coating may be applied as above for the typical case of simple revegetation (merely the weight of a few inches of back-fill soil being contemplated), a stronger, thicker layer for where any significant weight is to be applied, such as where a foundation for a gravel building pad or road is being formed. In such instances (or where any appreciable moisture is anticipated), it will be preferred to apply the urethane foam in a multi-Iaminate form. For instance, a seven-layer foam about 1.5 inches thick (the specific thickness depending on locale) has been found satisfactory for Prudhoe Bay pond crossings (more below). Here the foam is applied in successive layers (preferred range 4 to 7) each separated by a very high density laminar-skin a few mils thick (formed by sufficient exposure of the upper surface of each layerv to air). Of course, moisture should not be present except, perhaps, during the initial application time, the liquid substrate being understood as being solidly frozen thereafter.

PHASE 3 SEAL The urethane foam layer is then allowed to cure long enough to set up (here about 10 to 15 minutes) and then the protective barrier super-coating, or seal, is applied to protect against degradation of the foam by mechanical and liquid forces. Here, the sealpreferably takes the form of ARCOTE Barrier coat 1000 applied toa continuous uniform thickness of about 15 mils., being applied in the manner of the pre-coat described above and comprising the same material without the polymeric extenders.

Now the frozen, insulated sump pond is ready to be covered with soil and reseeded to develop tundra vegetation and thus restore the site. It is preferred (though not essential) that this phase of the treatment beperformed about break-up time (or around May 15 for Prudhoe Bay), since the berm fill will begin to be somewhat thawed and workable about then. This maypreferably and conveniently be done simply by rolling-back enough berm material to bring the sumpcavity up to grade since this berm is understood as largely comprised of top-soil (active layer) material intermixed with tundra type organic matter and thus especially well suited for planting. Of course, if necessary, one may haul in gravel, dune sand, etc., to establish the proper reseeding topsoil mix. The fill is preferably piled up slightly above grade so as to accommodate some minor subsidance and water run-off (e.g., from rain and snow melt). Reseeding will be performed in the manner above described except as otherwise noted here.

With the sump site now so filled, it is next, according to another feature of novelty, reseeded and fertilized with a prescribed tundra reseeding formulation to induce optimum revegetation and regrowth in the subject locale. Reseeding may be done at any convenient time when the appropriate equipment and personnel can get access to the site, often on the same day the insulation is applied and the sump filled in. The Reseeding Formulation developed for this locale comprises the following generic constituents: a special formulated tundra fertilizer; a localized mixture of cover crop seeds (an annual) which have been germination-induced; and a localized perennial seed mixture, selected for this 10- cale and adapted to induce regrowth that is quick to germinate and grow, is strong, and offers some resistance to winter-kill. This tundra fertilizer is especially formulated to supply the needed nutrients found to be missing in the Prudhoe locale (see soil analysis in Tables II and III, and discussion above). A preferred embodiment is the aforedescribed Tundra Special-" fertilizer (see Table IV). The preferred embodiment for this Prudhoe Reseeding Formulation is Prudhoe l-C", the constituents and dosages thereof being summarized in Table IX below.

TABLE IX RESEEDING FORMULA PRUDI-IOE ARCO Tundra Special 70 Fertilizer 300 lb,/acre Cover Grass Annual Rye 50 lbJacre Perennials":

Red Top Grass 8 lb./acre Creeping Red Fescue Grass l6 lh./acre Canada Blue Grass 8 IbI/acre The cover crop seed (Rye preferred here) is compatible with the Perennial and is chemically treated before application to accelerate germination as aforedescribed. The cover crop will act to stabilize the site during initial, delicate regrowth, holding the top-soil and retaining moisture while the perennial seed is taking hold.

The perennial mixture is selected to yeild seedlings that are capable of both germinating in the brief Prudhoe summer and offer a high degree of winter survival. The perennial grass seeds (see Table VI also regarding Red Top, Creeping Red Fescue and Canada Blue Grass) are preferably coated with a formulation to accelerate germination rates and increase seedling growth.

While reseeding usually may be performed at any time of the year, some grasses, such as Canada Blue, have been found to suffer inferior germination unless they are exposed to a freeze cycle, such as when they experience an arctic winter in the ground or when they are pre-chilled in cold storage for a time. It is believed that this affects certain enzymes, contributing to good germination. The reseeding formulation may be applied in any known, convenient manner, e.g. being distributed separately and incorporated into the topsoil with a harrow. For small areas like the subject sump, which are also within a few miles of operating base, manual application methods such as broadcasting are feasible. However, for larger areas or those more remote, aerial seeding from helicopter-borne unit will often be advisable, this being followed by ground incorporation, where needed.

For the present embodiment, the Prudhoe l-C reseeding formulation is preferably applied by manual broadcasting on top-soil of the frozen, filled site without any particular effort at incorporation. This formulation was tailored to the indicated soil analysis and the native tundra vegetation in the Prudhoe Bay locale. It will be understood that for other areas with different vegetative types and/or different soil analysis, appropriate modifications may be made by those skilled in the art. It has been noted that in certain instances some follow-on care is also advisable; for instance, where reseeding is followed by an unfavorable growing period (e.g., scanty precipitation, nutrient deficiencies), further fertilization, watering, or even supplemental reseeding, may be called for. In the present embodiment, it will be found that application of this formulation will result in revegetation and restoration of the site, integrating it with the ambient terrestrial environment, providing a solid, stable support under the reseeded soil with the sump liquid being kept frozen and incorporated as (quasi-permafrost or icing-in the sump pool) a part of the adjacent permafrost with no later subsidance, erosion, etc. Of course, this perennial cover vegetation is designed to be superceded eventually by a climax cover of the original native vegetation (re-invasion). Complete tundra regrowth, stability and ecological equilibrium should thus be restored within just a few Arctic seasons.

WINTER ROAD RESTORATION The concepts demonstrated in the foregoing mud sump restoration embodiment may also be applied to other related situations where relatively small, shallow, confined liquid deposits on the frozen plain may be insulation-sealed and rendered into a quasi permafrost" condition; and then overlain with various construction and/or ground cover materials. One example is restoration of winter roads of the type aforedescribed. It will be appreciated that winter roads are typically formed simply by scooping up tundra material and topsoil in a strip along the planned road-bed and piling it up to form the roadway (berm). Now, this typically leaves broad ditches paralleling the roadway berm which have been denuded of tundra vegetation. In such instances, and unfortunately, one or two summer seasons will usually develop ground-water pools in the ditches; these will grow with each summer-thaw, inducing run-off and galloping erosion. It will be apparent that the foregoing system taught for restoration of mud sumps may likewise be applied for restoration of such water ditches. Thus, one may apply the aforementioned insulation system (including a pre-coat and a barrier coat where appropriate) atop the frozen ditch-pools doing this during the winter freeze and covering the insulation with a suitable soil cover, (e.g., rolling back a part of the winter road berm now useless and abandoned), and thereafter reseeding and restoring the ground cover with an appropriate restoration system such as that aforedescribed (Table IX etc.).

It will further be apparent to those skilled in the art that such an icing-in" is applicable not only to waterditches (as with mud sumps) but may likewise be applied to other roads (not just winter roads) or embankments where a ponded condition" has resulted in depressions along an embankment shoulder or elsewhere; of course adapting the reseeding restoration tem in an appropriate manner to suit the given ambient environment.

Moreover, as a further improvement, the foregoing teaching may be adapted for restoring depressions on the frozen plain such as the described mud sump, winter road or other rain ditch situations etc., where the depressions are realtively dry, i.e., they either have no liquid therein or too little to suit (e.g. liquid level below grade). Nonetheless, in such situations where water or other applicable liquid is available for practical use, it will be seen that such a depression may be filled with liquid, then allowed to freeze, then insulated and restored to the surrounding grade and vegetative condition. For instance, during the winter season one may apply liquid in a fine spray to build up quickfrozen layers, creating a laminar iced-in system, and so artificially ice-in the depression to bring it up close to tundra-grade to be thereafter soil-filled and planted. This ice-in obviously conserves fill material (e.g., gravel ,which is quite precious in certain areas) quickly and inexpensively. Indeed, such a frozen pond substrate (akin to the sump embodiment) will be recognized by construction engineers as forming a hard, flat, stable, quasi-permafrost base which is a fine foundation for roads, building pads, etc. as long as it is kept frozen. For instance, such an ice footing under a gravel road will provide an especially hard solid, flat stable foundation as long as it is kept frozen. Indeed, in some situations (indicated elsewhere) it may even be desirable to create such a depression, fill it with liquid, freeze it, insulate it and build on this artificial permafrost according to the invention.

POND CROSSING As suggested above, the subject system is applicable for uses beyond simplytra'pping and stabilizing waste deposits underground (as quasi-permafrost) and will have application as a positive construction technique in certain instances. One of these is the typical Arctic pond situation where an Arctic road or embankment is planned across a route intersected by one or more small, shallow depressions, often filled to some extent with liquid and subject to melting. More particularly, and for example, where one is building a gravel road in the Prudhoe Bay locale, he will typically encounter a myriad of suchnatural ponds creating the well-known polygon formations on the North Slope. Such ponds comprise depressions on the order of a few yards in diameter by a few feet deep and these literally dot the Arctic pl'ainlTo circumvent all such Arctic ponds in laying out a roadway is usually impossible, and almost never practical even assuming one is unconcerned over how much time and trouble it takes to snake the road along the ridges between ponds.

Thus, for this pond crossing" embodiment, it will be understood that a gravel road is contemplated, measuring about feet high by about 15 feet wide (useful width; graded with shoulders extending about 4 feet out on each'side this constituting a gravel berm'overall about 23 feet wide). When the typical shallow polygon pond is encountered, it may be bracketed (completely covered) by the planned width of this gravel berm. It will be apparent that the aforementioned mudsump insulation technique, appropriately modified for the given circumstance, may be employed to provide a solid quasi-permafrost base for the road. However, -when only part of the pond lies along the path of this berm, it will often be practical to go to special lengths to freeze and insulate (ice-in) the entire pond nonetheless, and cover it with topsoil and revegetation in the pond area not covered by the road-berm the insulation being accordingly extended across the entire ponded surface to cover (ice-in) those areas not along the path of the intended highway. Ground cover, such as the tundra reseeding system mentioned in the first (pond stabilization) example, may then be superposed.

For such roadway foundations (or related loadbearing sites), it will be preferable to employ about 1.3 inch of the polyurethane mentioned in the first example for better structural support, applying this in a sevenlaminate system as described (assuming the Prudhoe Bay locale). However, foam thickness will, of course, depend upon ambient thermal driving conditions and vary with the thermal characteristics and history of the. site. For example, at either the Sagwon or the Galbraith locale (in Alaska), the polyurethane insulation thickness will be closer to 2 inches,-with the gravel supercover thickness being determined primarily by structural loading constraints. For heavier loading, and/or in cases where a severe ground moisture condition is contemplated, greater thicknesses and/or more laminations will be preferred. It should be appreciated by those skilled in the art that, although the aforedescribed road construction technique involves the extra expense of insulation (usually relatively minor) and, in certain cases, the expense of revegetation as well (over ponded areas that are wider than the roadway), this will be more than compensated-for by the resultant freedom of design which is achieved and by the associated savings in length-of-road (eliminating wending-about between ponds); as well as savings in bridges or culverts eliminated and by the extra stability supplied by the firm, stable quasi permafrost substratum developed.

LEVELING ARCTIC ROADS The principles of the invention illustrated above may be further applied in the leveling of roadways over tundra, providing an economic and structurally sound means of reducing cut and fill" problems. Workers in the art know that the North Slope or any such frozen plain typically presents a gently-rolling terrain that undulates up and down (several feet amplitude) regularly, every dozen yards or so in all directions. This undulation creates a cut and fill problem for the road engineer, requiring excavation and the need for a great deal of grave] or other fill (note that scraping or related leveling techniques cannot be used since the tundra ground cover must be kept intact). In cases where liquid water is available in the wintertime it will be apparent that, as with the aforedescribed icing-in of pond crossings (embodiment above), here, the depressions along the roadway may likewise be sprayed with water, frozen-in and insulated to provide an ice-fill up to within a few inches of the surrounding grade (being integrated with the subjacent permafrost) being thereafter covered with gravel, etc. it has been found that at least 6 inches of gravel should be applied.

An analogous treatment is advantageous for providing a quasi-permafrost footing under an arctic embankment. An example is for constructing a Building Pad as follows:

A Pad formulation area X 100 feet is worked out on the Prudhoe Bay tundra in the winter .season. Snow is piled up and compacted (sufficient to at least support a man) within this area to a uniform depth of about 3 feet. Liquid water is then sprayed atop this snow pad and allowed to freeze (in layers preferably a few inches thick each) in situ until abouttwo feet of ice is thus built up. Then, generally following the teachings of the prior embodiments (except where specified otherwise), a urethane foam cap is laid down atop the ice and down the sides of the ice-pad (to the extent it protrudes above-grade), to a thickness of about 1 /2 inches. A perimeter-form may be employed to contain the icefill and give vertical sides where desired. The pad (top and sides) is then covered with a structural pile" of gravel (Sagwon type) about 6-8 inches thick. Next a power house structure is constructed on the gravel pad to house a 30 KW generator complex. This structure will generate heat and must accordingly be thermally-insulated from the so-constructed quasipermafrost foundation. This generator is operated periodically according to need. Using thermo-couple data to monitor temperatures, it will be observed (over at least one or two seasons) that only a slight thawing will occur this, in the top 2-3 inches of the ice pad. Also,

resultant settlement will be found very minor (e.g. about 1-2 inches over two seasons using normal survey/leveling measurement techniques) with substantially no deterioration of the foam.

The foregoing will be surprising in several respects. It indicates that an ice-pad" (whether snow-ice as described; simply spray-on ice built up to the desired height, etc.) will provide a very satisfactory base for structures (e.g., embankment base for a drill pad or housing structure). The ease, convenience and time savings (also gravel savings) resulting will especially be appreciated (e.g., ice-in a drill pad during winter; set up operations next summer if desired). Moreover, the efficiency of a urethane foam cap" (assume foam as previously described) in maintaining the frozen (quasipermafrost condition of the ice base is demonstrated even in the face of heat input from a generator structure atop the pad. Of course, a proper K factor will be selected. Also, the adequacy of a few inches (6-8 inches described) a gravel top-cover as both a wear surface and protective mantle" for the foam is shown. Workers in the art will appreciate that such ice-pads can be provided using modified, equivalent expedients. For instance, a berm of snow (or frozen snow) may be provided as a perimeter barrier" or form within which the ice-pad may be built up. above grade; whereas, below grade a simple hole will often suffice.

tion tilted in one or several directions for quick run-off.

Workers in the art will recognize that the novel features of this disclosure may be applied, alone or together, in other contexts to solve different but related problems and that the implementation suggested in the foregoing embodiments may be modified to achieve the described results. For instance, where roadways were mentioned primarily in the embodiments, it will nonetheless be apparent that the same kind of restoration and construction techniques may be applied for gravel building pads or other embankments on frozen terrain. Similarly, for the insulating material; while urethane foam has been suggested in the embodiments, there will be instances, recognized by those skilled in the art, where other equivalent foams and other insulation can suffice (such as polystyrene foam or even ceramic materials or various natural materials in various forms). In particular, where inexpensive insulation is deisred, such coatings as petroleum-extended foams (e.g., extended with Prudhoe crude) or the like, may be applicable. In certain instances the incorporation of air or other blowing agents will be employed (e.g. conventional air-blowing techniques) so that the active hydrogen content of the material be increased, similar to what is done with asphalt coatings elsewhere. Likewise,

the revegetation techniques, it will be understood that, although those described were apt for the purposes and the locales mentioned, workers in the art will prefer different (though related) seeding and supportive fertilization and germination techniques for substantially different circumstances. For instance, while pretreating seeds as indicated with gibberellic acid (selectively, however, for each variety) gave rather surprising results (as did pre-treatment with potassium nitrate; in a different way, however), other known germination promoters such as ethylene, Kinetin or Thiourea will occur to workers as somewhat similarly applicable. Such expedients for enhancing germination and growth will be found to be important to a degree much more critical than in other (non-frigid) environments, for example, the special interaction, on grasses like those mentioned in North Slope regions, of low temperatures (low thaw-index, high freeze-index) with constant highwind conditions plus harmful insulation (incident radiation on surface-applied, non-incorporated seeds) and rather arid ground conditions are believed to constitute the principal cause of the unusually low germination rates, and/ or relatively high residual-germination conditions found to obtain. Also, workers will appreciate the surprisingly advantageous interaction of the described insulation and resotration (e.g., replanting) techniques. For instance, not only does such insulation seal-in a permafrots substratum and prevent later thaw and erosion from removing (replanted) ground cover, but the regrowth and the insulation supplement one another in certain respects the vegetation acts as a supplemental thermal shield once established; but, until it is, the insulation accelerates warming of the planted top-soil (adding to the thaw index of the site) and hastens regrowth. ln certain instances such a subsurface layer of artificial insulation can also be employed to conserve moisture; for instance, a relatively waterimpermeable insulation sheet covered with only a few inches of humus and replanted will obviously enhance revegetation for at least a few years in arid regions e.g., both melting snow cover earlier and conserving more melt run off.

In summary, although certain embodiments have been given by way of example and illustration, it will be obvious to those skilled in the art that various modifications of the materials and techniques described may be made without departing from the spirit and scope of the present invention as defined in the appended claims. For example, equivalent elements and steps may be substituted for those described, parts may be reversed and various features used independently of others, all without departing from the spirit of the invention.

What is claimed is:

l. A method of disposing of a prescribed volume of liquid or semi-liquid waste on the terrain of cold weather regions, this method comprising the steps of:

selecting or constructing a prescribed storage cavity in said terrain adapted to receive said volume of waste; filling said cavity with said wastes to a prescribed degree and allowing this deposit to freeze substantially solid at least at the upper level thereof; capping the upper surface of the so-frozen waste deposit with a layer of protective material including a prescribed thickness of artificial thermal insulation, sufficient to keep the deposit frozen and thus forestall melting and subsidence during a prescribed lifetime in the subject environment; and covering the so-coated frozen deposit with particulate soil fill to a prescribed level.

2. The method as recited in claim 1 wherein said waste comprises a volume of spent drilling mud and wherein said soil fill has characteristics similar to the native soil.

3. The method as recited in claim 1 wherein said protective layer includes a petroleum base top-seal coating including polymeric materials, this top-seal coating being applied as a weather seal over said insulation.

4. Themethod as recited in claim 3 wherein said protective layer comprises an initial coating of a crude petroleum product extended with polymeric materials with a few hundredths of an inch thereof being applied to the surface of the frozen deposit; and a one to two inch thickness of a rigid polyurethane foam insulation applied on this initial coating.

5. The method as recited in claim 1 wherein said insulation comprises a rigid polyurethane foam coating applied in several layers and adapted to support a prescribed structural load as well as to resist the instrusion of moisture vapor.

6. The method as recited in claim 1 including the steps of:

providing a perimeter-berm to at least prtly define the prescribed-cavity; excavating, after freezing of waste deposit held within this perimeter berm, the inner'perimeter of the berm to'deflne a ledge extending outward as an annular ring about the top perimeter of the frozen surface and tilted downwardly so as to define the locus of a brim annulus of insulation about the insulation cap to be overlaid on the frozen deposit, thereafter so coating the deposit as to define this insulation cap including the outward, downward-extending brim; and thereafter applying a particulate soil layer as a protective mantle over the insulation cap and the disposal site.

7. The method of claim 1 wherein said particulate soil fill is treated to enhance early restoration thereon of native ambient ground cover vegetation.

8. The method of claim 1 wherein said particulate soil fill is replanted to induce native revegetation.

9. The method of claim 1 wherein said particulate soil fill is seeded with selected cover-crop seeds.

10. The method of claim 9 wherein said seeds are perennial seeds selected from the group consisting of Red Top, Creeping Red Fescue, Canada Blue and Brome.

11. A method of leveling and stabilizing the surface terrain of areas in the Arctic regions characterized by depressions comprising (a) filling the depressions to a predetermined level with frozen material (b) coating thefrozen materials of the filled depression substantially entirely with sufficient artificial insulation material to keep it frozen for a prescribed period of time (c) covering the insulation material with a layerof particulate soil material to bring the level of the filled in depression up to the level of the surrounding terrain and (d) treating said particulate soil material with fertilizer containing those nutrients which are necessary to sustain the growth of desired vegetation and of which said particulate soil is deficient.

12. The method of claim 11 wherein said particulate soil material is seeded with selected cover-crop seeds.

l 3. The method of claim 12 wherein said seeds are perennial seeds selected from the group consisting of Red Top, Creeping Red Fescue, Canada Blue and Brome.

14. A method of leveling and stabilizing the surface terrain of areas in the Arctic regions characterized by depressions comprising (a) filling the depressions to a predetermined level with frozen material (b) depositing a layer of polymer-extended petroleum crude material on the frozen material (0) coating the petroleum crude material substantially entirely with sufficient artificial insulation material to keep it frozen for a prescribed period of time and (d) covering the insulation material with a layer of particulate soil material to bring the level of the filled in depression up to the level of the surrounding terrain.

'Inventor(s) UNITED s'm'me EPATEN'E omm I CERTWECATE OF CORRECTWN Patent 3,818a7ll Dated Fur-1e- 5: 9

Albert C. Condo and Joseph Neubauer It is certified that'error appears in the above-identified patent and that said Lettem Patent are hereby oom'ecfized ee shown below:

Second inventors-name should read -Joseph Neubauerriot "Joseph J. N. Neubauer".

Claim 5, line 4, "instrusiori" should read -intrusion-e.

Claim 6, line 3, "prtly" should read -partly Signed and sealed this 15th day of October 1974 e 4 (SEAL) A ttest:

MCCOY M. GIBSON JR. C, MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A method of disposing of a prescribed volume of liquid or semi-liquid waste on the terrain of cold weather regions, this method comprising the steps of: selecting or constructing a prescribed storage cavity in said terrain adapted to receive said volume of waste; filling said cavity with said wastes to a prescribed degree and allowing this deposit to freeze substantially solid at least at the upper level thereof; capping the upper surface of the so-frozen waste deposit with a layer of protective material including a prescribed thickness of artificial thermal insulation, sufficient to keep the deposit frozen and thus forestall melting and subsidence during a prescribed ''''lifetime'''' in the subject environment; and covering the so-coated frozen deposit with particulate soil fill to a prescribed level.
 2. The method as recited in claim 1 wherein said waste comprises a volume of spent drilling mud and wherein said soil fill has characteristics similar to the native soil.
 3. The method as recited in claim 1 wherein said protective layer includes a petroleum base top-seal coating including polymeric materials, this top-seal coating being applied as a weather seal over said insulation.
 4. The method as recited in claim 3 wherein said protective layer comprises an initial coating of a crude petroleum product extended with polymeric materials with a few hundredths of an inch thereof being applied to the surface of the frozen deposit; and a one to two inch thickness of a rigid polyurethane foam insulation applied on this initial coating.
 5. The method as recited in claiM 1 wherein said insulation comprises a rigid polyurethane foam coating applied in several layers and adapted to support a prescribed structural load as well as to resist the instrusion of moisture vapor.
 6. The method as recited in claim 1 including the steps of: providing a perimeter-berm to at least prtly define the prescribed cavity; excavating, after freezing of waste deposit held within this perimeter berm, the inner perimeter of the berm to define a ledge extending outward as an annular ring about the top perimeter of the frozen surface and tilted downwardly so as to define the locus of a ''''brim'''' annulus of insulation about the insulation cap to be overlaid on the frozen deposit, thereafter so coating the deposit as to define this insulation cap including the outward, downward-extending ''''brim''''; and thereafter applying a particulate soil layer as a protective mantle over the insulation cap and the disposal site.
 7. The method of claim 1 wherein said particulate soil fill is treated to enhance early restoration thereon of native ambient ground cover vegetation.
 8. The method of claim 1 wherein said particulate soil fill is replanted to induce native revegetation.
 9. The method of claim 1 wherein said particulate soil fill is seeded with selected cover-crop seeds.
 10. The method of claim 9 wherein said seeds are perennial seeds selected from the group consisting of Red Top, Creeping Red Fescue, Canada Blue and Brome.
 11. A method of leveling and stabilizing the surface terrain of areas in the Arctic regions characterized by depressions comprising (a) filling the depressions to a predetermined level with frozen material (b) coating the frozen materials of the filled depression substantially entirely with sufficient artificial insulation material to keep it frozen for a prescribed period of time (c) covering the insulation material with a layer of particulate soil material to bring the level of the filled in depression up to the level of the surrounding terrain and (d) treating said particulate soil material with fertilizer containing those nutrients which are necessary to sustain the growth of desired vegetation and of which said particulate soil is deficient.
 12. The method of claim 11 wherein said particulate soil material is seeded with selected cover-crop seeds.
 13. The method of claim 12 wherein said seeds are perennial seeds selected from the group consisting of Red Top, Creeping Red Fescue, Canada Blue and Brome.
 14. A method of leveling and stabilizing the surface terrain of areas in the Arctic regions characterized by depressions comprising (a) filling the depressions to a predetermined level with frozen material (b) depositing a layer of polymer-extended petroleum crude material on the frozen material (c) coating the petroleum crude material substantially entirely with sufficient artificial insulation material to keep it frozen for a prescribed period of time and (d) covering the insulation material with a layer of particulate soil material to bring the level of the filled in depression up to the level of the surrounding terrain. 